Has anyone taken the trouble of removing the honeycomb within the front exhaust piece (1st preconverter)? Has this resulted in any net gain in performance? Does this result in damage to other exhaust components?

Emissions testing is not required in my state for my '86 GXL.

Thanks for your input

 

You can smash it out with a crowbar. You don't need the precats or main cat, if emissions aren't a concern. Removing them will allow for a decent power gain, but it will also make the exhaust louder. The best route, however, would be to use an aftermarket header, a presilencer or straight pipe and a catback system.

 

NA's have 2 precats. You should just look at them and if they are still good(not melted or broken) keep them and replace the pipe with a RB downpipe or header.

I guted a few cats on these cars and if it is clogged you will notice a butt dyno diffrence. If they are not clogged then you might notice a little throttle response but otherwise not much.

Gutting the precats sends all the heat to the main cat. Over lots of miles if will cause it to fail. They all fail eventually. You MUST KEEP the main cat for backpressure. I have passed CA smog with the main cat only.

 

as always, you guys come through with the goods. Thanks for the info guys.

 

.

 

Forgot to mention that part. Opening up the exhaust fully will stop the aux. port actuators from opening, which results in roughly -25 hp. Alternatively, the ports can be rigged to open via air pump pressure, but that's another story.

And the precats are there for cold starting emissions. Once up to operating temp, the main cat is doing all of the work. I also pass CA smog regularly with only a main cat.